1.java向ios推送消息有现成的类库java APNS可以使用，github地址：https://github.com/notnoop/java-apns

2.官网上给出了使用的demo：

//Setup the connection
ApnsService service =
    APNS.newService()
    .withCert("/path/to/certificate.p12", "MyCertPassword")
    .withSandboxDestination()
    .build();
//Create and send the message
String payload = APNS.newPayload().alertBody("Can't be simpler than this!").build();
String token = "fedfbcfb....";
service.push(token, payload);

首先是构造一个ApnsService，需要传递证书，然后就是构造消息内容，然后就是发送，使用起来相当的简单。

3.当部署到线上服务器以后，发现推送消息非常慢，有时候7,8分钟才能返回，我在做推送的时候怕阻塞主线程，用了一个线程池异步来发消息的，很有可能是线程池沾满了，后续的消息就发不出去了。

jstack打印堆栈，发现了大量名为“MonitoringThread-1”的线程，而且状态还都是RUNNABLE的！

<pre name="code" class="html">"MonitoringThread-1" daemon prio=10 tid=0x00007f0d381bf800 nid=0x481a runnable [0x00007f0d147f2000]
   java.lang.Thread.State: RUNNABLE
	at java.net.SocketInputStream.socketRead0(Native Method)
	at java.net.SocketInputStream.read(SocketInputStream.java:152)
	at java.net.SocketInputStream.read(SocketInputStream.java:122)
	at sun.security.ssl.InputRecord.readFully(InputRecord.java:442)
	at sun.security.ssl.InputRecord.read(InputRecord.java:480)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:927)
	- locked <0x00000000f6219d18> (a java.lang.Object)
	at sun.security.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:884)
	at sun.security.ssl.AppInputStream.read(AppInputStream.java:102)
	- locked <0x00000000f6222d08> (a sun.security.ssl.AppInputStream)
	at com.notnoop.apns.internal.ApnsConnectionImpl$2.readPacket(ApnsConnectionImpl.java:241)
	at com.notnoop.apns.internal.ApnsConnectionImpl$2.run(ApnsConnectionImpl.java:153)
	at java.lang.Thread.run(Thread.java:745)

可以看出来是阻塞在了socket的read()上，先查下 MonitoringThread-1是在哪里创建的？

<pre name="code" class="java">private synchronized void sendMessage(ApnsNotification m, boolean fromBuffer) throws NetworkIOException {
        logger.debug("sendMessage {} fromBuffer: {}", m, fromBuffer);
        ...........
        while (true) {
            try {
                attempts++;
                Socket socket = getOrCreateSocket(fromBuffer);
                socket.getOutputStream().write(m.marshall());
                socket.getOutputStream().flush();
                cacheNotification(m);

                delegate.messageSent(m, fromBuffer);

                //logger.debug("Message \"{}\" sent", m);
                attempts = 0;
                break;
            } catch (IOException e) {
                 .....

</pre><pre name="code" class="java"><pre name="code" class="java">private synchronized Socket getOrCreateSocket(boolean resend) throws NetworkIOException {
        ..........
        if (socket == null || socket.isClosed()) {
            try {
                ........
                socket.setSoTimeout(readTimeout);
                socket.setKeepAlive(true);
                if (errorDetection) {
                    monitorSocket(socket);
                }
               ............
        }
        return socket;
    }

private void monitorSocket(final Socket socket) {
        logger.debug("Launching Monitoring Thread for socket {}", socket);

        Thread t = threadFactory.newThread(new Runnable() {
            final static int EXPECTED_SIZE = 6;

            @SuppressWarnings("InfiniteLoopStatement")
            @Override
            public void run() {
                logger.debug("Started monitoring thread");
                try {
                    InputStream in;
                    try {
                        in = socket.getInputStream();
                    } catch (IOException ioe) {
                        in = null;
                    }

                    byte[] bytes = new byte[EXPECTED_SIZE];
                    while (in != null && readPacket(in, bytes)) {
                       ................
                    
            }
	}
}

public ApnsConnectionImpl(SocketFactory factory, String host, int port, Proxy proxy, String proxyUsername, String proxyPassword,
                              ReconnectPolicy reconnectPolicy, ApnsDelegate delegate, boolean errorDetection, ThreadFactory tf, int cacheLength,
                              boolean autoAdjustCacheLength, int readTimeout, int connectTimeout) {
        this.factory = factory;
        this.host = host;
        this.port = port;
        this.reconnectPolicy = reconnectPolicy;
        this.delegate = delegate == null ? ApnsDelegate.EMPTY : delegate;
        this.proxy = proxy;
        this.errorDetection = errorDetection;
        this.threadFactory = tf == null ? defaultThreadFactory() : tf;
        this.cacheLength = cacheLength;
        this.autoAdjustCacheLength = autoAdjustCacheLength;
        this.readTimeout = readTimeout;
        this.connectTimeout = connectTimeout;
        this.proxyUsername = proxyUsername;
        this.proxyPassword = proxyPassword;
        cachedNotifications = new ConcurrentLinkedQueue<ApnsNotification>();
        notificationsBuffer = new ConcurrentLinkedQueue<ApnsNotification>();
    }

private ThreadFactory defaultThreadFactory() {
        return new ThreadFactory() {
            ThreadFactory wrapped = Executors.defaultThreadFactory();
            @Override
            public Thread newThread( Runnable r )
            {
                Thread result = wrapped.newThread(r);
                result.setName("MonitoringThread-"+threadId.incrementAndGet());
                result.setDaemon(true);
                return result;
            }
        };
    }

这里我们看到了“MonitoringThread-1”的来源，可以看出来，只要设置了errorDetection参数，如果socket是null或者没有连上，就会新起一个线程来读响应，我们在调用的时候每次使用完毕就把service给close掉了，导致每次发消息socket都会重建，就会多出一个线程来，并且线程的id始终都是1.只要把errorDetection设置为false就可以了。</p><p>4.在ApnsService的build的时候，我们发现了另一个有用的参数：isQueued：

<pre name="code" class="java">public ApnsService build() {
        ...............
        service = new ApnsServiceImpl(conn, feedback);

        if (isQueued) {
            service = new QueuedApnsService(service, queueThreadFactory);
        }
        
        if (isBatched) {
            service = new BatchApnsService(conn, feedback, batchWaitTimeInSec, batchMaxWaitTimeInSec, batchThreadFactory);
        }
        service.start();
        return service;
}

我们默认创建的ApnsServiceImpl，通过这个参数可以设置为QueuedApnsService，这个就比较有用了，发消息的时候，网消息队列里扔进入就ok了，正是我们所需要的：

public class QueuedApnsService extends AbstractApnsService {

	private static final Logger logger = LoggerFactory.getLogger(QueuedApnsService.class);
	
    private ApnsService service;
    private BlockingQueue<ApnsNotification> queue;
    private AtomicBoolean started = new AtomicBoolean(false);

    public QueuedApnsService(ApnsService service) {
        this(service, null);
    }

    public QueuedApnsService(ApnsService service, final ThreadFactory tf) {
        super(null);
        this.service = service;
        this.queue = new LinkedBlockingQueue<ApnsNotification>();
        this.threadFactory = tf == null ? Executors.defaultThreadFactory() : tf;
        this.thread = null;
    }

    @Override
    public void push(ApnsNotification msg) {
        if (!started.get()) {
            throw new IllegalStateException("service hasn't be started or was closed");
        }
        queue.add(msg);
    }

    private final ThreadFactory threadFactory;
    private Thread thread;
    private volatile boolean shouldContinue;

    public void start() {
        if (started.getAndSet(true)) {
            // I prefer if we throw a runtime IllegalStateException here,
            // but I want to maintain semantic backward compatibility.
            // So it is returning immediately here
            return;
        }

        service.start();
        shouldContinue = true;
        thread = threadFactory.newThread(new Runnable() {
            public void run() {
                while (shouldContinue) {
                    try {
                        ApnsNotification msg = queue.take();
                        service.push(msg);
                    } catch (InterruptedException e) {
                    	// ignore
                    } catch (NetworkIOException e) {
                    	// ignore: failed connect...
                    } catch (Exception e) {
                    	// weird if we reached here - something wrong is happening, but we shouldn't stop the service anyway!
                    	logger.warn("Unexpected message caught... Shouldn't be here", e);
                    }
                }
            }
        });
        thread.start();
    }

    public void stop() {
        started.set(false);
        shouldContinue = false;
        thread.interrupt();
        service.stop();
    }

    @Override
    public Map<String, Date> getInactiveDevices() throws NetworkIOException {
        return service.getInactiveDevices();
    }

    public void testConnection() throws NetworkIOException {
        service.testConnection();
    }

}

因此，最终我们构造ApnsService的时候是类似于这样的：

service = APNS.newService().withCert(cert, password).withSandboxDestination().asQueued().withNoErrorDetection().build();